Hydraulic method and apparatus for flexing stuck pipe in well bores



July 9, 1963 E. D. HALL HYDRAULIC METHOD AND APPARATUS FOR FLEXING v v STUCK PIPE IN WELL BORES Original Filed Dec. 12, 1956 3 Sheets-Sheet l JNVENTOR. E//Wef' Ha July 9, 1963 E D HALL 3,096,822

HYDRAULIC METHOD .AN APPARATUS FOR FLEXING STUCK PIPE 1N WELL BORES Original Filed Dec. l2, 1956 3 Sheets-Sheet 2 i INVENTOIL E/mer' 0. /707/ July/9, 1963 E. D. HALL HYDRAULIC METHOD AND APPARATUS FDR FLExING sTucx` PIPE: 1N WELL BoREs 12. 195e Y Original Filed Dec.

3 Sheets-Sheet 3 M .llll

INVENTR. /mef' y Ha// l||||||ll EHIIMM United States Patent original application Dee. 12, 1956, ser. No. 627,935, newv Patent No. 2,939,531, dated June 7, 1960. Divided and this application Oct. 19, 1959, Ser. No. 847,148

9 Claims. (Cl. 166-35) This invention relates to methods and apparatus for freeing stuck pipe in well bores and refers more particularly to such methods and apparatus wherein a material length is inserted within the pipe to be freed and moved therethrough into the stuck area, force then being applied within the -length to flex it in the well bore and the pipe to be freed therewith.

This application is a continuation-impart of my previous application, Serial No. 601,579, filed August l, 1956, now Patent No. 2,956,626 and is also a division of my application Serial No. 627,935 tiled December 12, 1956, now Patent No. 2,939,531.

Stuck pipe in this disclosure is to mean any type of pipe which has been lowered into a well bore for the purpose of drilling for, or production of, water, oil, gas, etc., and has become lodged in the Well bore in such a manner that it cannot be lowered or withdrawn by present methods of longitudinal tension (pulling on the pipe to its yield point) or compression (applying the weight of the free pipe in the .well bore downwardly upon the lodged or stuck pipe). Thus, the term stuck will described pipe lodge in a well bore under the condition described above.

One of the major concerns in finishing an oil well is l sticking of the pipe and actually getting the pipe to the bottom of the hole. It would be extremely desirable to be able to guarantee a job of getting the pipe to the bottom or keeping it free in the well bore if it is to be removed therefrom. Previously, this has not been possible.

A number of conditions can actually happen in a well bore to stick pipe therein. These conditions can be enumerated as follows:

(l) Where loose formations such as sand or shale have settled around the pipe in the annulus between the outside of the pipe and the face of the Well bore in a suflicient quantity to cause enough friction that the pipe cannot be moved longitudinally or in rotation.

(2) Where a coupling or any other device that is on the pipe which is of a larger diameter than the pipe becomes lodged in what is referred to in oil well drilling terminology as a key seat. A key seat is actually an enlargement in one side of the drilled well bore caused by the movement of the pipe, either in rotation or in longitudinal movement, against the inside curve or bend opposite a bend or curve in the well bore. In such a condition, the pipe is held against the inside curve or bend by the tension of pipe hanging below it, causing the pipe to wear away that side of the well bore to the same sine of the pipe itself. In other words, a key seat is an attempt by the pipe in tension to straighten out or remove any deviations of the well bore from a straight line. Unlder these conditions, any object of a larger diameter than the size of the well bore at this key sea-t will tend to become wedged when forced into it. In actual oil well drilling practice, the size of a key seat is determined by the tool joints or couplings on the drill pipe, and it is usually any device that has a larger diameter than the tool joints that may become lodged therein.

(3) Where large objects in the hole, such as boulders, or broken or lost pieces of drilling tools become wedged between the pipe and the well bore, causing the pipe to stick.

(4) Yet another condition in a well bore which may stick pipe is differential pressure. In differential pressu-re high pressure fluid in the annulus between the casing and the well bore ows into a porous subterranean formation which has a natural pressure far less than that of the annulus uid. When this condition occurs, the casing cleaves or seizes to the permeable portion of the borehole wall under the influence of the differential pressure. If the casing actually comes into contact with the porous or permeable formation, it acts as a seal over a greater or lesser area thereof and is thus forced against that region by an 'amount equal to the annulus pressure minus the forma-tion pressure times the actual area of contact ybetween the" casings exterior wall and the wall of the well bore. Thus, for example, if the annulus fluid pressure exceeds the formation pressure by 1800 pounds per square inch, while the area of casing and borehole wall contact is 500 square inches. the casing will be driven against the borehole wall by a total force of 400,000 pounds. It is obvious, that as long as these conditions are maintained, there is little hope of moving the casing further into the bore or removing it therefrom. The reason for this is, in the latter case, that both the casing weight and ythe shear strength of the contact plane must be overcome.

One of the great problems in oil well drilling is to salvage stuck pipe. Hundreds of millions of dollars of pipe are left in wells every year and only approximately 30% of the total pipe set in wells can be salvaged at present. Up to thepresent time, it has been possible only to salvage the casing down to the first oil sand in a multiple oil horizon well because the first sand or any permeable area thereabove causes sticking of the pipe by differential pressure.

In my above mentioned previous application, I disclosed various forms of rigid curved or crooked metallic lengths which could be jammed or otherwise forced into stuck pipe to the vicinity of the stuck portion thereof and, once there, either rotated and moved into the stuck area or forced without rotation through the stuck area. This constructioninvolved a rigid metallic length crooked o r curved to a greatest diameter -beyond that of the pipe to be freed, the length thus distoring the pipe to be freed as it is forced therethrough. While this modification is effective, in some situations, especially where used or weakened pipe is involved, it is not desirable to employ this construction of the pipe freeing apparatus. It has been desirable, therefore, to provide methods and apparatus of flexing the stuck pipe in the vicinity of the stuck area thereof without previously distorting or flexing the pipe in the insertion of the flexing means. The provision of such methods and apparatus is one of the objects of this invention.

Therefore, an object of the invention is to provide method and apparatus for freeing pipe which is stuck in a well bore eciently and dependably.

Another object of the invention is to provide methods and apparatus for freeing pipe stuck in a well bore where the pipe is stuck due to settling of well material, key seat engagement, wedging or differential pressure.

Another object of the invention is to provide methods and apparatus for freeing pipe stuck in a well bore wherein pipe stuck in a plurality of positions in a well bore can be freed and, particularly, pipe stuck` against a plurality of permeable sands by differential pressure can be freed.

Another object of the invention is to provide methods and apparatus for freeing pipe stuck in a well bore which will greatly increase the percentage quantity of pipe which is salvageable from well bores, such salvage saving great quantities of both money and metal.

Another object of the invention is to provide apparatus for fiexing the pipe to be -freed in the well bore which will iiex the'pipe in any direction desired sequentially without rotation of the device within the pipe t be freed.

Yet another object of the invention is to provide apparatus for fiexing the pipe to be freed in a well bore wherein the means for fiexing the device in the pipe to be freed are co-mpletely enclosed by the device at all stages in the flexing procedure.

Another object of the invention is to provide methods and apparatus for`freeing pipe stuck in boreholes, the method and apparatus being applicable to free cemented pipe where the bond is not complete or the cement has been contaminated, for example, it being common in oil well cement jobs to have several hundred feet of contaminated cement at the top of the cemented portion.

Otherand further objects of the invention will appear in the course of the following description thereof.

In the drawings, which form a part of the instant specification and are to be read in conjunction therewith, embodiments of the invention are shown and, in the various views, like numerals are employed to indicate like parts. v .x A j FIG. 1 is a cross-Sectional lview through an earth formation showing la`.lfi`r'st modification of the inventive apparatus for freeing stuck pipe in a well bore positioned in a casing or pipe in a well bore, the casing just having been flexed in a well bore to free it from its previously stuck position.

FIG. 2 isla detail view of several of the individual sections of the apparatus of FIG. l with parts in section and cut away to show the interior construction for fiexing the device, the unit shown in the straight position.

YFIG. 3 isfa detail view of a similar portion of the apparatus of FIG. 1 with parts cut away and in section to show the internal construction of the flexing means, the unit shown in the exed position.

FIG. 4 is a view taken along the lines 4-4 of FIG. 2 in the direction of the arrows.

FIG. 5 is a view taken along the lines 5 5 of FIG. 2 in the direction of the arrows.

FIG. 6 is a cross-sectional view through an earth formation showing a second modification of the inventive apparatus for freeing stuck pipe in a well bore positioned in a casing or pipe in a well bore, the casing just having been fiexed in the well bore to free it from its previously stuck position.

FIG. 7 is a detail view of a portion of the device shown in FIG. 6 with parts cut away and in section to show the internal construction of the liexing means, the portion shown in the straight or unflexed position.

FIG. 8 is a detail view similar to that of FIG. 7 of a portion of the device of FIG. 6 with parts cut away and in section to show the construction of the flexing means, the portion shown in the fiexed position.

FIG. 9 is a view taken along the lines 9-9 of FIG. 7 in the direction of the arrows.

FIG, 10 is a view taken along the lines 10--10 of FIG. 7 in the direction of the arrows.

FIG. 11 is a cross-sectional view through an earth formation showing a third modification of the inventive apparatus for freeing stuck pipe in a well bore positioned in a casing therein, the apparatus just having been flexed in the well bore to free the casing from its previously stuck condition.

FIG. 12 is a side elevation of the construction of FIG. 11 with a portion broken away to illustrate the internal construction of the device and parts in dotted lines for the same purpose, the unit shown in the straight position.

FIG. 13 is a cross-sectional view through an earth formation showing a fourth modification of the inventive apparatus for freeing stuck pipe in a well bore positioned in a casing or pipe in the well bore, the apparatus just having been iiexed in the well bore to free the casing from its previously stuck condition.

yIFIG. `i4 is a side elevation of the FIG. 13 modification with parts broken away to show the internal construction of the apparatus, the unit shown in the straight position.

Referring to the drawings, and to the modification of the invention shown in FIGS. 1 5, earth formation 10 contains well bore 11 extending downward-ly therethrough. Casing or pipe 12 has been run in the well bore 11 and has become stuck thereto by one of the previous listed difficulties adjacent the point indicated at 12a. The inventive device for freeing casing stuck in the well bore comprises a fiexible length generally designated at 13 having means at its upper end therefor for moving it through the pipe to be freed. In the example shown in the drawings, this latter means comprises a threaded upper portion 14 of the device enga-geable with `a threaded portion 15 of a conventional dril-l stem 16. The body 13 of the length consists of a multiplicity of sections 17 strung on a relatively fiexible, centrally positioned mandrel 18 (FIGS. 2-5). The sections `17 are r-adiused or rounded on both ends thereof as at 17a so as to allow flexing or bending of the mandrel 18 carrying sections 17 with a minimum of elongation of the total length 13. The sections 17, which are positioned centrally of the ends of the length 13, are furnished with one or more bores 19 running therethrough substantially parallel to the mandrel 18. In the example shown Iin the drawings, four of these bores are formed in the sections positioned equal angular distances apart. Within the bores 19, stretchable hydraulic tubing 20 of reinforced rubber or like suitable material is enclosed and prevented from extrusion or pinching between the sections 17 by means of the metal sleeves 2l which extend through the gaps lbetween the sections 17. Sleeves 21 are fixed or welded to one of the sections each penetrates and slidably mounted in the other.

The upper end fitting 22, besides having the threaded portion 14 therein, has hydraulic fiuid feedways 23 therein to -feed fiuid to the tubings 20 either from tubes extending downwardly in bore 16a of the drill stem 16 or the drill stem bore 16a itself with a valve means (not shown) controlling 'the tiow between the various bores. At the lower end of the length 13 is preferably rounded end fitting 24 threaded onto threaded extension 25 of the lowest section 17b. The bores 19 and tubings 20 are sealed in the lowest section `17b to prevent extrusion or release of fiuid there-from. The upper and lower end fittings 22 and 24 retain the sections 17 0n the mandrel 18 preferably under mild tension.

When the tubings 20 in the bores 19 are inflated singly, or in pairs on the same side of the length 13, the stretching of the tubing will cause distortion or exing of the apparatus as in FIG. 3. It is necessary, of course, that the tubing 20 be of sufiicient strength to hold sufficient pressure to distort the casing. The length 13 itself is preferably of an outer diameter only slightly less than the inner diameter of the pipe to be freed whereby any fiexion of the length itself will be transmitted to the casing around it and the casing itself -will be flexed -in the well bore. By increasing and releasing the hydraulic pressure in any one side of the length, the length may be repeatedly exed in a single direction. By alternately raising and releasing the pressure in opposite sides of the length, the casing may be exed in opposite directions or at any angles desired. In this manner the casing 12 may be freed within the well bore 11. The length of the device 13 is preferably less than the length of a conventional length of pipe (thirty feet in oil wells) but this limitation is not necessary. The amount of fiexion possible in the device preferably should not exceed the elastic limit of the pipe to be freed. The flexion of the casing is limited by the annular space between the casing and well bore but the strain on the pipe may be varied by varying t'ne length of the flexing device.

In operation, the device '13 is inserted in the pipe to be freed and run therethrough at the end of drill stem 16. In one variation of the method, the device 13 may be stopped immediately above the stuck section and fiexed and then gradually .moved into the stuck portion flexing periodically as it is moved. In another variation of the method, the device .13 may be moved right opposite the stuck section and then flexed therein. When the easing or pipe 12 has been freed, the device 13 m\ay,be removed on the drill stem 16 andthe casing 12 itself removed Ifrom the well bore or run lower therein if desired. If, as previously set forth, the length 13 is moved gradually downwardly, continuing flexion, until the area of greatest flexion (centrally) of the device yis opposite the cleavage area or stuck portion, the destruction of the cleavage plane of the casing 12 to the formation 10 in a differential pressure sticking wi-ll be progressive rather than entire and simultaneous. The len-gth may be moved entirely below the stuck portion while flexing if desired. When the casing 12is wedged, blocked or in a key seat, it is easy to see that such flexion, if necessary, in all directions, will serve to breakup and displace the wedging material to free the pipe. In a differential pressure sticking the passage of the well bore fluids into the permeable zone packs and dehydrates the mud in the wel-l bore against the permeable zone and, once the casing is free, it will not readhere.

Additionally, the flexion of the length relative the stuck portion of the casing will mash the heavy thick mud -into the Iformation pore space and serve to seal off the permeable formation even more and, therefore, the tendency will be -for the casing not to restick.

When there are several permeable formations or stuck portions of the casing, the length 13 may be moved first above the first stuck zone, then flexed and moved with periodic exing into the stuck zone to free it (or run -into the zone and fiexed). Once that zone has been cleared, the length may then be moved downwardly to a position above the second stuck zone, flex-ion begun and then the length -moved into the zone while flexing. (Or run directly into the zone and exed.) In this manner, the pipe may be freed from an indefinite number of stuck zones and the running of the casing to the Ibottom of the hole or its removal from the hole may be guaranteed. Once the stuck areas have been freed, the 4drill stem 16 and length 13 are withdrawn from the casing. Contaminated or faulty cement jobs will sometimes leave casing or pipe -in such a condition of adherence to the well bore that Y the inventive length may be able to flex or beat several hundred feet of the casing free `from the faulty bond to permit the recovering thereof.

It would be understood relative all four modifications of the invention shown in the fourteen figures, that while the cylindrical form (in cross section) is preferred on all of the devices shown in the drawings and described in the specification, any desired form, triangular, square, hexagonal, etc., in cross section may be employed so long as the greatest diameter of the cross-sectional form is not greater than the inside diameter of the pipe to be freed. The usefulness of the cylindrical form :lies in its minimizing of friction and localized wear on the pipe as it passes therethrough and is rot-ated therein.

Referring to FIGS. 6-10, therein is shown a second modification of the invention device for freeing casing in well bores. In FIGS. 6 at 26 is shown an earth formation having a well bore 27 extending downwardly therethrough with casing 28 having been run in the well bore. The inventive apparatus for freeing pipe stuck in a well bore comprises in this modification a flexible metal length normally extending relatively straight, the length, as in the previous modification, having an outer diameter sufficiently less than the pipe to be freed to be inserted therein and moved therethrough, means at the upper end of the length for moving it through the pipe to be freed, and means associated with the length whereby to ex it within the pipe to be freed and the pipe to be freed therewith and free the latter in -the well bore. The length 29 comprises high strength tubing which is milled or sawed partially through on one side thereof to provide a plurality of hinge kerfs 30. The kerfs 30 being positioned on one side of the tubing serve to weaken that side to flexing stress. The kerfs 30 extend essentially the entire length of the device save for the upper and lower ends thereof, the former having threaded inner portion 31 to engage the drill stem 32 and the latter comprising rounded lower end fitting 23 which engages threaded extension 34 on the lower end ofthe length 29. Flexible tubing 35 (FIGS, 7 and 8) of reinforced rubber or other suitable substance extends essentially the length of the inventive device 29 and may be inflated hydraulically by fluid forced through the drill stern 32. The tubing 35 is sealed at its lower end adjacent the lower fitting 33. Pinching or bursting .of the tubing 35 through the kerfs 30 is prevented by the metal liner 36 extending between the tubing 35 and length 29 the length of the latter whose hinge kerfs 37 are midway between those of the outer tubing or casting 29. Hydraulic inflation of the tubing 35 within the wkened casing 29 will cause the latter to distort or flex as shown in FIG. 8, this flexion also flexing the casing 28 which it is positioned within. Release of the hydraulic pressure will permit the -tubing or casing 29 to resume its normal for-m. ,'Ihe strength of the tubing must be sufficient to withstand suflicient pressure to deform the length 29 and casing 28.

The operation of this second modification of the invention is the same as that shown in FIGS. 1-5 with the exception that the casing 29 must be rotated at the end of dn'll stem 32 to flex the outer casing 28 in another direction from that originally caused. Thus, once the length 29 is mounted on the drill stem 32, it may be run either to a position above the stuck portion of the pipe or to a position opposite it. If it is run to a position above, the casing 29 may be flexed either in one position or in verious angular positions within the casing 28 and moved gradually into the stuck portion of the pipe. In this manner the destruction of the cleavage plane of the casing 28 to the well bore wall will be gradual. Otherwise, the length may be moved right into the stuck portion and fiexed and rotated for further flexion as desired. The casing 29 may be moved completely through the stuck portion of the casing in a process of periodic flexion if desired. In a differential pressure sticking, the flexion of the length relative the stuck portion of the casing will mash the heavy, thick mud into the formation pore space and serve to sealsolf the permeable formation, and therefore, the tendency will be for the casing not to restick. 'Ifhe oper-ation relative several permeable for-mations or stuck portions of the casing is the same as recited relative the FIGS. l-5 modification. As in the FIGS. l-S modification, the length of the device is not critical but is preferably less than the standard length of a section of pipe to be inserted in the well bore (in oil wells, conventionally 30 feet). lf the length is limited in this manner, easier handling and use.result.

Referring to the third modification of the invention shown in FIGS. 1I and l2, therein is shown a modification of the invention similar to that of FIGS. l-5 with the exception that the bores 19 which contain the tubings 20 of the FIGS. l-5 modification are pitched within the length in the FIGS. 11-12 modification whereby to spirally run around the length. By pitching of the bores in the sections of the length, the device can be caused to take a spiral form when pressurized. Alternation of pressure from one tubing bore to the next will, in fact, cause a. whipping or snaking motion.

In FIG. 11, earth formation 38 has borehole 39 extending downwardly therethrough. Casing 40 has been run in the well bore 39 and was stuck adjacent 39a. Length 41 having a plurality of sections 42 mounted centrally thereof has upper and lower fittings 41a and 41h attached thereto. 'Ihe sections 42 are preferably rounded on each end thereof whereby to maintain the device of the same length when the device is flexed. Sections 42 and the upper and lower fittings are mounted on mandrel.

43 which extends centrally of the sections. Fittings 41a and lb preferably maintain the sections 42 on the manel under slight tension. The length 41 is attached at its upper end to drill stem 44. A plurality of bores 45 extend through the sections and contain flexible tubing 46 of reinforced rubber or other suitable material therein. Tubings 46 must be of sufficient strength to withstand any pressures applied hydraulically thereto and are sealed pass through. Preferably, the bores are pitched so that a. given bore 45 extends at -least once completely around the mandrel 43 to complete a 360 spiral. The angular deflection of any given bore from its original position may be either less or greater than 360, but the latter is preferred.

in operation, when there is no hydraulic pressure applied to any of the tubings d6, the ngth 41 -hangs straight. lt may be inserted in the casing 40 with the rounded lower end 41b aiding in insertion. After the length has been inserted into the casing 40, it is run at the end of drill stem 44 either to a position slightly above or a position opposite the stuck portion of the casing 180. If the length 41 is positioned above the stuck portion, the spiral flexion of the length 41 may be begun by raising and releasing the pressure in one or more tubings d6 on a side of the length or the pressure may be alternated back and forth between sides to give the whipping or snaking motion previously noted. lf the length was stopped above the stuck area, it may be moved gradually into the stuck area with periodic flexion to gradually destroy the cleavage plane of the casing to the wall or other obstruction. lf moved directly opposite the stuck portion, it may be flexed there as desired until the casing is freed. As previously recited relative the other modifications, the length may be moved opposite or relative a plurality of struck zones to free them in one casing. When the casing is freed, the length may be removed from the well and the casing itself may be either moved to the bottom of the hole or removed as desired. The FIG. ll illustration shows the pitched bore modification in the spiral flexed position with one side of the bores expanded.

The fourth modification of the invention is shown in FIGS. l3-14 and is related to the FIGS. 6-10 modification. In FIG. 13, 48 indicates the earth formation, 49 the borehole extending downwardly therethrough and 50 the casing which was previously stuck at an area 'in the vicinity of 49a. Length 5l of high strength tubing has hinge kerfs 52 sawed or milled into the length to weaken areas of the tubing. 'Ihe kerfs 52 are so positioned on the tubing relative one another that they spiral therearound. lThis is clearly seen in FIG. 13. Rounded end tting 53 is threaded onto the lower end of the tubing and seals the lower end thereof. The upper end is threaded to dril-l stem 54. As seen in FIG. 14, flexible tubing 55, of reinforced rubber or other suitable resilient substance, is enclosed between the tubing and metal liner 56. Liner 56 has spirally positioned hinge kerfs 57 vertically spaced between the kerfs 52 and prevents pinching or bursting of the tubing 55 through the outer kerfs 52. The tubing 55 is sealed at its lower end adjacent or within the bottom fitting 53 and hydraulic uid may be communicated with the tubing either through the drill stem 54 itself or through a flow line therewithin extending to the surface. Tubing 55 is of a strength to withstand any pressures applied thereto.

The operation of the FIGS. 13-l4 modification is the same as those previous in that the length 51 be moved either above or opposite the stuck zone and flexion begun. lf the -length 51 is above the stuck zone, it is moved into the zone gradually with periodic flexion. The length 51, as in the case of the FIGS. 1l-l2 modification, may be rotated on the drill stern 54 as desired so the form of the spiral will be taken at different angular positions within the casing 50.

It should be noted that in all four modifications or variations of the invention, that, if desired, the length 13, 29, 41 and 51 may -be moved to a position adjacent (above or opposite) the stuck zone, then flexed to any desired form, and then, with the tool or length in flexed position, forced downwardly through the casing to be freed into and, if desired, through the stuck portion. In this manner, the flexed length deforms or distorts the casing as it is forced therethrough. The hydraulic devices within the lengths to cont-rol their flexion must have suflicient strength to deform both the length and casing it moves through.

All of the lengths shown inthe drawings and described in the specifications preferably have an outside diameter only slightly less than the inside diameter of the pipes to be freed. The mandrel in the lengths of FIGS. 1-5 and 11-12 must be of suflicient strength to support the weight of the length and the distortions thereof but must be of sull'cient flexibility to deform under application of the hydraulic pressure to the lengths. The sleeve surrounding the hydraulic tubings, to avoid extrusion thereof from the bores carrying the tubing, must be of sufficient strength to withstand any hydraulic pressure applied to the tubing.

From the foregoing it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth together with other advantages which are obvious and which are inherent to the structures and methods. I

lt will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and snbcombinations.

This is contemplated by and is within the scope of the claims.

As many possible embodiments may -be made of the invention without departing from the scope thereof, it is to be understood that al-l matter herein set forth is to be interpreted as illustrative and not in a limiting sense.

Having thus described my invention, I claim:

l. A method of freeing pipe stuck in a well bore comprising the steps of running a laterally flexible, elongated member into the stuck area of the pipe, flexing said member within said pipe and the pipe therewith, allowing said member and pipe to straighten, then flexing said member and pipe therewith in another direction without rotation of said member within the pipe and again permitting the body and pipe to straighten.

2. A method of flexing pipe stuck in a well bore employing a flexible material body insertable within the pipe to be flexed and movable therethrough, comprising the steps of running said body to a level above the stuck area of the pipe to be flexed, flexing said body and the pipe therewith, moving said body, while still in the flexed position downwardly through the stuck portion of the pipe, deforming the pipe as it is moved downwardly therethrough and permitting the body and pipe to straighten after the body has been moved into at least a portion of the stuck portion of the pipe to be flexed.

3. Apparatus for flexing pipes stuck in a well bore comprising an elongated hollow body, means to propel said body into a stuck pipe, there being structure incorporated in opposite sides of said body of substantially varying longitudinal elasticity, and means for applying fluid pressure to the interior of said body and thereby causing longitudinal flexure thereof for flexing the encompassing pipe.

4. Apparatus for flexing pipe st uck in a well bore comprising an elongated hollow body of flexible material and of less diameter than the pipe for which it is intended, there being structure of substantially varying longitudinal elasticity incorporated in opposite sides of said body and an expansible sealed chamber within said body, means to propel said body into a pipe, and means to apply pressured fluid to said chamber for expanding the same and thereby causing longitudinal ilexure of said body and the encompassing pipe.

5. Apparatus as described in claim 4 in which said structures of varying elasticity extend helically around said body whereby internal pressuring of said body will cause helical distortion of said body.

6. Apparatus as described in claim 4 in which said body, when unstressed, is substantially straight longitudinally.

7. Apparatus for freeing stuck pipe comprising an elongated shell of exible material having at least one circumferential cut extending pai ially therearound, means to propel said` shell into` a stuck pipe, an expansiblel envelope in said shell, and means to introduce pressured 10 uid into said envelope to cause longitudinal exure of said shell and the encompassing pipe.

8. Apparatus as described in claim 7 including a plu rality of said partial circumferential cuts spaced longitudinally along said shell.

9. Apparatus as described in claim 8 in which said partial circumferential cuts are substantially parallel and ranged in a helical pattern along and around said shell.

References Cited in the tile of this patent UNITED STATES PATENTS 1,837,690 Sunde Dec. 22, l93-l 2,242,279 Young May 20, 1941 2,340,959 Harth Feb. 8, 1944 2,382,933 Zublin Aug. 14, 1945 2,441,881 Hays May 18, 1948 2,730,176 Herbold Ian. l0, 1956 2,778,603 McCune et al. Jan. 22, 1957 2,939,531 Hall June 7, 1960 

2. A METHOD OF FLEXING PIPE STUCK IN A WELL BORE EMPLOYING A FLEXIBLE MATERIAL BODY INSERTABLE WITHIN THE PIPE TO BE FLEXED AND MOVABLE THERETHROUGH, COMPRISING THE STEPS OF RUNNING SAID BODY TO A LEVEL ABOVE THE STUCK AREA OF THE PIPE TO BE FLEXED, FLEXING SAID BODY AND THE PIPE THEREWITH, MOVING SAID BODY, WHILE STILL IN THE FLEXED POSITION DOWNWARDLY THROUGH THE STUCK PORTION OF THE PIPE, DEFORMING THE PIPE AS IT IS MOVED DOWNWRDLY THERETHROUGH SAID PERMITTING THE BODY AND PIPE TO STRAIGHT- 